Disk cartridge

ABSTRACT

A disk cartridge in which a pair of shutter members can be opened and closed smoothly and reliably, and a dust-proof property and an airtightness of a large opening portion can be increased by reducing a space between a pair of shutter members and a cartridge housing as much as possible. The disk cartridge comprises a cartridge housing in which a disk compartment is formed between an upper shell and a middle shell by overlapping the upper shell, the middle shell and the lower shell and the middle shell is supported by the upper shell and the lower shell so as to become freely rotatable, an optical disk rotatably stored within the disk compartment and a pair of shutter members attached to the middle shell in such a manner that they can be moved in the plane direction on the same plane. A shutter opening and closing mechanism for opening and closing opening portions by moving the pair of shutter members based rotation of the middle shell.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a disk cartridge having acartridge housing in which a disk-like recording medium such as anoptical disk, a magnetooptical disk and a magnetic disk is stored in adisk compartment so as to become freely rotatable, and particularly to adisk cartridge in which a pair of shutter members are opened and closedto open and close an opening portion by rotating a middle shell whichforms a disk compartment between it and an upper shell or a lower shelland a part of a disk-like recording medium is exposed from the openingportion when the opening portion is opened.

DESCRIPTION OF THE RELATED ART

[0002] As a disk cartridge in which a disk-like recording medium inand/or from which audio information, video information or informationsuch as computer data can be recorded and/or reproduced is rotatablystored in a cartridge housing, there is known a disk cartridge having anarrangement shown in FIG. 27, for example. This disk cartridge 1 is adisk cartridge incorporating therein a write once magnetooptical disk 4in which a user can record and write information such as computer datalater on. This disk cartridge has an appearance shown in FIG. 27.

[0003] This disk cartridge 1 includes a cartridge housing 2 comprised ofa pair of an upper shell 2a and a lower shell 2b, a magnetooptical disk4 rotatably stored within a disk compartment 3 of this cartridgehousing, and the like. The cartridge housing 2 has on its upper andlower surfaces defined an upper and lower opening portion 5 which isextended from the central portion to one side. This opening portion 5can be opened and closed by a shutter member 6 which can be slid alongone side. Reference numeral 6a designates a presser member which canprevent the tip end portion of the shutter member 6 from beingextracted.

[0004] A disk-like metal center hub 7 is provided at the central portionof the magnetooptical disk 4. This center hub 7 is disposed at theposition opposing to the inner end portion of the opening portion 5,i.e., at substantially the central portion of the cartridge housing 2. Aturntable provided on an information recording and reproducing apparatusbody side is mounted on this center hub 7 and the magnetooptical disk 4is fixed to the center hub by chucking of the turntable, whereby themagnetooptical disk 4 is rotated at a predetermined velocity (e.g.,constant linear velocity). In this case, an information signal isrecorded on or reproduced from the magnetooptical disk 4 by action of amagnetooptical pickup device whose head portion is inserted into theopening portion 5.

[0005] However, in the conventional disk cartridge having the abovearrangement, the shutter member 6 which opens and closes the openingportion 5 has a U-like shaped cross-section. This shutter member 6 isfitted into one side of the cartridge housing 2 and the shutter member 6is slid along one side of the cartridge housing to thereby open andclose the opening portion 5. For this reason, it is unavoidable that alarge space is produced between the cartridge housing 2 and the shuttermember 6, and therefore the disk cartridge cannot be prevented frombeing smudged by very small dusts and the like.

[0006] In recent years, in the stream in which an optical disk isincreasing its storage capacity/increasing its recording density, arecording pattern is becoming narrower in pitch and is increasing alinear density. When a recording surface of an optical disk or amagnetooptical disk is smudged by dusts, read or write beam is shieldedor when the information recording surface of the optical disk is damagedby scratches, information cannot be read or written normally. For thisreason, in the conventional disk cartridge, as shown in FIG. 27, theshutter member 6 having substantially the U-like shaped cross-section isattached to one side of the cartridge housing 2 so as to become slidableand is slid along one side of the cartridge housing thereby to open andclose the opening portion 5 so that the information recording surface ofthe optical disk or the like can be protected.

[0007] However, as the optical disk is further increasing a storagecapacity/increasing a recording density, very small dusts which are notso influential in the prior art becomes more influential over readingand writing of data. Therefore, the shutter member having the aboveU-like shape cannot prevent the disk cartridge from being smudged byvery small dusts. In this case, when the information recording surfaceof the magnetooptical disk 4 is smudged by very small dusts entered intothe cartridge housing 2, the information recording surface of themagnetooptical disk is damaged by dusts so that information cannot beread out from and written in the magnetooptical disk normally.

[0008] In the above conventional disk cartridge 1, the shutter member 6is located on the disk cartridge at its position in which users caneasily touch the shutter member. There is then the risk that a user willslide the shutter member 6 to open the opening portion 5 by mistake. Inaddition, since the shutter member 6 is linearly slid along one side ofthe cartridge housing 2, there arises a problem that the surface area ofthe cartridge housing 2 cannot be reduced.

SUMMARY OF THE INVENTION

[0009] In view of the above problems encountered with the conventionaldisk cartridge, it is an object of the present invention to provide adisk cartridge in which the above problems can be solved and in which amiddle shell is made rotatable and a pair of shutter members are openedand closed based on the rotation of the middle shell whereby the pair ofshutter members can smoothly and reliably be opened and closed and adustproof property and airtightness of the large opening portion can beimproved by reducing a space between the pair of shutter members and thecartridge housing as much as possible.

[0010] In order to solve the above problems and in order to attain theabove objects, a disk cartridge according to claim 1 of the presentinvention is comprised of a cartridge housing in which a diskcompartment is formed between an upper shell and a middle shell orbetween the middle shell and a lower shell by overlapping the uppershell, the middle shell and the lower shell and in which the middleshell can be supported by the upper shell and the lower shell so as tobecome freely rotatable, a disk-like recording medium rotatably storedwithin the disk compartment and a pair of shutter members attached tothe middle shell in such a manner that they can be moved in the flatsurface direction on the same plane, wherein a shutter opening andclosing mechanism for opening and closing an opening portion by movingthe pair of shutter members based on the rotation of the middle shell isprovided.

[0011] A disk cartridge according to claim 2 of the present invention ischaracterized in that the pair of shutter members are comprised of acombination of two substantially semicircular same plate materials andthe shutter members are symmetrically disposed on one surface side ofthe middle shell across the opening portion.

[0012] A disk cartridge according to claim 3 of the present invention ischaracterized in that the shutter opening and closing mechanism includesrotary coupling portions respectively provided on one side portions ofthe pair of shutter members and which are coupled to the middle shell soas to become freely rotatable and movement coupling portionsrespectively provided on the other side portions of the respectiveshutter members and which are coupled to the lower shell or the uppershell so as to become movable relatively, and the shutter opening andclosing mechanism opens and closes the opening portion by rotating thepair of shutter members around the rotary coupling members based on therotation of the middle shell to thereby relatively move the movementcoupling portions.

[0013] A disk cartridge according to claim 4 of the present invention ischaracterized in that the rotary coupling portion is comprised of acombination of a shaft portion provided on one of the pair of shuttermembers and the middle shell and an engagement hole provided on theother of the pair of shutter members and the middle shell, the movementcoupling portion is comprised of a combination of a guide grooveprovided on one of the pair of shutter members and the lower shell orthe upper shell and an operation convex portion provided on the other ofthe pair of shutter members and the lower shell or the upper shell, andthe pair of shutter members are enabled to open and close by moving theguide groove along the operation convex portion based on the rotation ofthe middle shell.

[0014] A disk cartridge according to claim 5 of the present invention ischaracterized in that the opening portion is extended in the lineardirection through respective central portions of the middle shell andthe lower shell or the middle shell and the upper shell.

[0015] A disk cartridge according to claim 6 of the present invention ischaracterized in that an elevation mechanism for moving the middle shellin the direction perpendicular to the rotation direction based on therotation of the middle shell so that the middle shell is pressed againstthe lower shell or the upper shell is provided.

[0016] A disk cartridge as claimed in claim 7 of the present inventionis characterized in that the shutter opening and closing mechanismincludes a pair of guide grooves provided on one of the pair of shuttermembers and the cartridge housing and a pair of operation convexportions provided on the other of the pair of shutter members and thecartridge housing and which are slidably engaged with the guide groovesand the pair of shutter members are enabled to open and close theopening portion by moving the guide grooves along the operation convexportions based on the rotation of the middle shell.

[0017] A disk cartridge as claimed in claim 8 of the present inventionis characterized in that the pair of shutter members are comprised of acombination of a pair of substantially semicircular same platematerials, the pair of shutter members are symmetrically disposed on onesurface side of the middle shell across the opening portion, the guidegrooves are provided on one side portions of chord sides of therespective shutter members and pivots provided on the other sideportions of the chord sides are supported by the middle shell so as tobecome freely rotatable.

[0018] A disk cartridge as claimed in claim 9 of the present inventionis characterized in that the elevation mechanism is comprised of aplurality of circular-arc-like cam grooves or cam convex portionsprovided in the circumferential direction of the upper shell or thelower shell at a predetermined interval and which are concaved orconvexed in the direction in which the upper shell, the middle shell andthe lower shell are overlapped and cam convex portions or cam groovesprovided in the circumferential direction of the middle shell at apredetermined interval and which are slidably engaged with the camgrooves or the cam convex portions.

[0019] A disk cartridge according to claim 10 of the present inventionis characterized by comprising a gear portion provided on the outerperipheral surface of the middle shell over a predetermined range of thecircumferential direction and an opening window from which a part of thegear portion is exposed and which is bored through the side surface ofthe upper shell and the lower shell.

[0020] A disk cartridge according to claim 11 of the present inventionis characterized in that the pair of shutter members are comprised of acombination of a pair of substantially semicircular same platematerials, the pair of shutter members are symmetrically disposed on onesurface of the middle shell across the opening portion, the guide grooveis provided on one side portion of a chord side in each of the shuttermembers and a shaft portion provided on the other side portion of thechord side is rotatably supported by the middle shell.

[0021] A disk cartridge according to claim 12 of the present inventionis characterized in that a pair of guide grooves are provided on one ofthe pair of shutter members and the cartridge housing, a pair ofoperation convex portions which are slidably engaged with the guidegrooves are provided on the other of the pair of shutter members and thecartridge housing, the guide grooves are moved along the operationconvex portions based on the rotation of the middle shell, whereby thepair of shutter members are enabled to open and close said open andclose portion.

[0022] A disk cartridge according to claim 13 of the present inventionis characterized in that the opening portion is extended in the lineardirection through central portions of the middle shell and the lowershell or the middle shell and the upper shell.

[0023] With the above arrangement, in the disk cartridge comprising thecartridge housing having the disk compartment, the disk-like recordingmedium and the pair of shutter members, since the disk cartridge asclaimed in claim 1 of the present invention includes the shutter openingand closing mechanism for moving the pair of shutter members based onthe rotation of the middle shell, the pair of shutter members cansmoothly and reliably be rotated by rotating the middle shell.Therefore, the disk compartment can be prevented from being smudged byvery small dusts and the like by reducing the space between the pair ofshutter members and the cartridge housing, and the dustproof property ofthe cartridge housing can be improved. Moreover, the disk cartridge canhe reduced in thickness and improved is space factor so that the wholeof the disk cartridge can be made compact and thin.

[0024] In the disk cartridge as claimed in claim 2 of the presentinvention, since the pair of shutter members are comprised of acombination of two substantially semicircular same plate materials, theopening portion of the wide range can be opened and closed while theareas of the shutter members are being reduced, Thus, while anefficiency with which the opening portion is opened and closed is beingincreased, the whole of the disk cartridge can be made compact and thin.

[0025] In the disk cartridge as claimed in claim 3 of the presentinvention, since the shutter opening and closing mechanism includes therotary coupling portion and the movement coupling portion so that thepair of shutter members are opened and closed based on the rotation ofthe middle shell to thereby open and close the opening portion, the pairof shutter members can smoothly and reliably be rotated.

[0026] In the disk cartridge as claimed in claim 4 of the presentinvention, since the rotary coupling portion is comprised of acombination of a shaft portion and an engagement hole and the movementcoupling portion is comprised of a combination of a guide groove and anoperation convex portion, the pair of shutter members can be operatedwith high reliability and the opening portion can smoothly and reliablybe opened and closed.

[0027] In the disk cartridge as claimed in claim 5 of the presentinvention, since the opening portion is extended in the diametricaldirection through the central portions of the middle shell and the like,two head portions can simultaneously be faced into the opening portion,whereby two operations (e.g., writing and reading of information signalcan be carried out, writing or reading of two places can be carried outsimultaneously, etc.) can be carried out at the sane time.

[0028] In the disk cartridge as claimed in claim 6 of the presentinvention, comprising the cartridge housing having the disk compartment,the disk-like recording medium and the pair of shutter members, sincethe disk cartridge comprises the shutter opening and closing mechanismfor opening and closing the opening portion by moving the pair ofshutter members based on the rotation of the middle shell and theelevation mechanism for moving the middle shell in the directionperpendicular to the rotation direction based on the rotation of themiddle shell, the pair of shutter members can smoothly and reliably berotated by rotating the middle shell and the middle shell can beascended and descended and pressed against the upper shell or the lowershell when the middle shell is rotated. Therefore, the space can beremoved or reduced by closely contacting the middle shell with the uppershell or the lower shell so that the disk compartment can be preventedfrom being smudged by very small dusts and the like, thereby improvingthe dustproof property of the cartridge housings. Moreover, thethickness of the cartridge housing can be decreased and the space factorcan be improved and the whole of the disk cartridge can be made compactand thin.

[0029] In the disk cartridge according to claim 7 of the presentinvention, since the pair of guide grooves are provided on one of thepair of shutter members and the cartridge housing and the pair ofoperation convex portions are provided on the other of the pair of guidegrooves and the pair of operation convex portions and the guide groovesare moved along the operation convex portions based on the rotation ofthe middle shell, the pair of shutter members can smoothly and reliablybe moved, whereby the opening portion of the wide range can be openedand closed.

[0030] In the disk cartridge according to claim 8 of the presentinvention, since the pair of shutter members are comprised of thecombination of two substantially semicircular same plate materials, theguide grooves are provided on one side portions of the respectiveshutter members, the pivots are provided on the other side portions andthe pivots are supported by the middle shell so as to become freelyrotatable, the opening portion of the wide range can be opened andclosed while the areas of the shutter members are being reduced. Thus,an efficiency with which the opening portion is opened and closed can beincreased, and the whole of the disk cartridge can be made compact andthin.

[0031] In the disk cartridge according to claim 9 of the presentinvention, since the cam grooves or the cam convex portions are providedon the upper shell or the lower shell and the cam convex portions or thecam grooves are provided on the middle shell to thereby constitute theelevation mechanism, the pair of shutter members can be sandwiched bythe upper shell or the lower shell and the middle shell as the middleshell is rotated, the space can be removed by closely contacting themiddle shell with the upper shell or the lower shell so that the diskcompartment can be prevented from being smudged by very small dusts andthe like. Thus, the dustproof property of the cartridge housing can beimproved.

[0032] In the disk cartridge including the cartridge housing having thedisk compartment, the disk-like recording medium and the pair of shuttermembers, according to the disk cartridge as claimed in claim 10 of thepresent invention, since the gear portion formed around the outerperipheral surface of the middle shell is exposed from the openingwindow provided on the side surface of the upper shell and the lowershell, the middle shell can be rotated by the simple shutter opening andclosing mechanism such as the rack rod disposed on the outside, and thepair of shutter members can smoothly and reliably be rotated based onthe rotation of the middle shell. Therefore, the shutter opening andclosing mechanism can be constructed extremely easily. In addition, thedisk compartment can be prevented from being smudged by very small dustsand the like by miniaturizing the space between the pair of shuttermembers and the cartridge housing. Thus, the dustproof effect of thecartridge housing can be improved and the disk cartridge can bedecreased in thickness and improved in space factor. There can beachieved the effects that the whole of the disk cartridge can be madecompact and thin.

[0033] According to the disk cartridge as claimed in claim 11 of thepresent invention, since the disk cartridge has the arrangement in whichthe pair of shutter members are comprised of a combination of the sametwo substantially semicircular plate materials, the respective shuttermembers are symmetrically disposed across the opening portion, the guidegrooves are provided on one side portions of the chord sides of therespective shutter members and the shaft portions provided on the otherside portions are rotatably supported to the middle shell, the openingportion of the wide range can be opened and closed while the areas ofthe shutter members are being decreased. Thus, an efficiency with whichthe opening portion is opened and closed can be improved and the wholeof the disk cartridge can be made compact and thin.

[0034] According to the disk cartridge as claimed in claim 12 of thepresent invention, since the disk cartridge has the arrangement in whichthe pair of guide grooves are provided on one of the pair of shuttermembers and the cartridge housing and the pair of operation convexportions are provided on the other of the pair of shutter members andthe cartridge housing so that the guide grooves may be moved along theoperation convex portions based on the rotation of the middle shell, thepair of shutter members are opened and closed by the rotation of themiddle shell to thereby open and close the opening portion, and hencethe pair of shutter members can be rotated smoothly and reliably.

[0035] According to the disk cartridge as claimed in claim 13 of thepresent invention, since the disk cartridge has the arrangement in whichthe opening portion is extended through the central portion of thecartridge housing to the diametrical direction of the disk-likerecording medium, the two head portions can be inserted into and ejectedfrom the opening portion simultaneously so that the two head portionsare faced into the opening portion simultaneously and two operations(e.g., writing and reading of an information signal, writing or readingof an information signal at two places at the same time, etc.) can becarried out simultaneously.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036]FIG. 1 is an exploded perspective view showing a disk cartridgeaccording to a first embodiment of the present invention andillustrating the same disk cartridge from the lower surface side;

[0037]FIG. 2 is a perspective view showing the disk cartridge shown inFIG. 1 from the lower surface side and illustrating the state in whichan opening portion is closed by closing a shutter mechanism;

[0038]FIG. 3 is a perspective view showing the disk cartridge shown inFIG. 1 from the lower surface side and illustrating the state in whichthe opening portion is opened by opening the shutter mechanism;

[0039]FIG. 4 is a plan view showing a lower surface of an upper shell ofthe disk cartridge shown in FIG. 1;

[0040]FIG. 5 is a plan view showing a lower surface of a middle shell ofthe disk cartridge shown in FIG. 1;

[0041]FIG. 6 is a plan view showing an upper surface of a lower shell ofthe disk cartridge shown in FIG. 1;

[0042]FIG. 7 is a perspective view showing the state in which an openingportion is opened by opening a pair of shutter members attached to themiddle shell of the disk cartridge shown in FIG. 1;

[0043]FIG. 8 is a perspective view showing the state in which theopening portion is closed by closing the pair of shutter membersattached to the middle shell of the disk cartridge shown in FIG. 1;

[0044]FIG. 9 is a perspective view showing the state in which a shuttermechanism is disposed on the lower shell of the disk cartridge shown inFIG. 1 and in which the opening portion is opened by opening the pair ofshutter members;

[0045]FIG. 10 is a perspective view showing the state in which theshutter mechanism is disposed on the lower shell of the disk cartridgeshown in FIG. 1 and in which the opening portion is closed by closingthe pair of shutter members;

[0046]FIG. 11 is a plan view showing the disk cartridge shown in FIG. 10from the upper direction;

[0047]FIG. 12 is a longitudinal cross-sectional view of the centralportion of the disk cartridge shown in FIG. 1 and to which referencewill be made in explaining a relationship between the disk cartridge anda turntable;

[0048]FIG. 13 is an explanatory diagram showing a relationship betweenoperations of a cartridge housing and a shutter mechanism of the diskcartridge shown in FIG. 1 and illustrating the state in which theopening portion is completely closed by closing the pair of shuttermembers;

[0049]FIG. 14 is a plan view showing the outward appearance state ofFIG. 13 from the lower shell side;

[0050]FIG. 15 is an explanatory diagram showing the state in which themiddle shell is rotated a little from the state shown in FIG. 13 so thatthe pair of shutter members are opened a little;

[0051]FIG. 16 is an explanatory diagram showing the state in which themiddle shell is further rotated a little from the state shown in FIG. 15so that the pair of shutter members are further opened a little;

[0052]FIG. 17 is an explanatory diagram showing the state in which themiddle shell is still further rotated from the state shown in FIG. 16 sothat the pair of shutter members are still further opened a little;

[0053]FIG. 18 is an explanatory diagram showing the state in which themiddle shell is still further rotated from the state shown in FIG. 17 sothat the pair of shutter members are still further opened a little;

[0054]FIG. 19 is an explanatory diagram showing the state in which themiddle shell is yet further rotated so that the pair of shutter membersare opened completely;

[0055]FIG. 20 is a diagram to which reference will be made in explainingthe manner in which the middle shell is ascended and descended relativeto the upper shell when the disk cartridge shown in FIG. 1 is opened andclosed, wherein FIG. 20A is an exploded perspective view, FIG. 20B is aperspective view showing the state in which the middle shell isdescended and FIG. 20C is a perspective view showing the state in whichthe middle shell is ascended;

[0056]FIG. 21 is a diagram to which reference will be made in explainingthe manner in which the middle shell is ascended and descended when thedisk cartridge shown in FIG. 20 is opened and closed, wherein FIG. 21Ais a cross-sectional view showing the state in which a cam portion ofthe middle shell is urged against a lift up portion of the upper shelland FIG. 21B is a cross-sectional view showing the state in which a camportion of the middle shell is inserted into a cam groove of the uppershell;

[0057]FIG. 22 is an exploded perspective view showing a disk cartridgeaccording to a second embodiment of the present invention andillustrating the disk cartridge from the lower surface side;

[0058]FIG. 23 is a perspective view showing the disk cartridge shown inFIG. 22 from the lower surface side and illustrating the state in whichthe opening portion is closed by closing the shutter mechanism;

[0059]FIG. 24 is a block diagram to which reference will be made inexplaining a circuit arrangement of a disk recording and reproducingapparatus which uses the disk cartridge according to the presentinvention;

[0060]FIG. 25 is a perspective view showing the state presented beforethe disk cartridge shown in FIG. 1 is inserted into the disk recordingand reproducing apparatus which uses the disk cartridge according to thepresent invention;

[0061]FIG. 26 is a perspective view showing the state in which the diskcartridge shown in FIG. 1 is being inserted into the disk recording andreproducing apparatus which uses the disk cartridge according to thepresent invention; and

[0062]FIG. 27 is a perspective view showing a conventional diskcartridge.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0063] Embodiments of the present invention will be described below withreference to the accompanying drawings. FIGS. 1 to 26 are diagramsshowing disk cartridges according to the embodiments of the presentinvention. Specifically, FIG. 1 is an exploded perspective view showinga disk cartridge according to a first embodiment from a lower shellside. FIG. 2 is a perspective view showing the same disk cartridge withits shutter being closed from the lower shell side. FIG. 3 is aperspective view showing the same disk cartridge with its shutter beingopened. FIG. 4 is a bottom view of an upper shell. FIG. 5 is bottom viewof a middle shell. FIG. 6 is a plan view of the lower shell. FIG. 7 is aperspective view showing the middle shell and a pair of shutter membersbeing opened. FIG. 8 is a perspective view showing the state in whichthe pair of shutter members shown in FIG. 7 are being opened. FIG. 9 isa perspective view showing the lower shell and the pair of shuttermembers being opened. FIG. 10 is a perspective view showing the state inwhich the pair of shutter members shown in FIG. 9 are being closed. FIG.11A is a plan view of FIG. 10. FIG. 12 is an explanatory diagram showingthe central portion in cross-section.

[0064] FIGS. 13 to 19 are explanatory diagrams showing a relationshipbetween the rotation amount of the middle shell and the opened andclosed states of the pair of shutter members, respectively. FIGS. 20A to20C are explanatory diagrams showing a relationship between the rotationof the middle shell and the ascending and descending operations,respectively. FIGS. 21A and 21B are explanatory diagrams showing thestate in which the shutter members are closely contacted/released basedon the ascending and descending operations executed when the middleshell is rotated. FIG. 22 is an exploded perspective view showing a diskcartridge according to a second embodiment from a lower shell side. FIG.23 is a perspective view showing the same disk cartridge from the lowershell side with the shutter closed. FIG. 24 is a block diagram to whichreference will be made in explaining a circuit arrangement of aninformation disk recording and reproducing apparatus which can use theinventive disk cartridge according to an embodiment of the presentinvention. FIG. 25 is a perspective view showing the state presentedbefore the disk cartridge according to the present invention is insertedinto the disk recording and reproducing apparatus. FIG. 26 is aperspective view showing the state in which the disk cartridge is beinginserted into the same disk recording and reproducing apparatus.

[0065] A disk cartridge 10 according to the first embodiment storestherein a read-only optical disk on which various information signalssuch as a music signal serving as audio information and a video signaland a music signal, both serving as video information, are recorded inadvance or an optical disk (write once optical disk) on which aninformation signal such as audio information and video information canbe recorded only once or an optical disk (rewritable optical disk) 11 onwhich an information signal can be recorded many times repeatedly as adisk-like recording medium. However, the disk-like recording medium isnot limited to the above optical disks, and a magnetic disk in whichinformation can be memorized by magnetic status of a specific positionon a magnetic thin layer formed on the surface of a thin disk, amagnetooptical disk in which information can be written in and read outfrom the magnetic thin layer formed similarly by using an optical headand a magnetic head and other storage mediums can be applied as theabove disk-like recording medium.

[0066] As shown in FIGS. 1 to 3, this disk cartridge 10 comprises acartridge housing 12 formed by overlapping a pair of an upper shell 13,a middle shell 14 and a lower shell 15, an optical disk 11 stored withina disk compartment 16 formed within this cartridge housing 12 so as tobecome freely rotatable, a pair of shutter members 18 a, 18 b foropening and closing opening portions 25, 42 bored through the middleshell 14 and the lower shell 15, and the like. In this disk cartridge10, when the optical disk 11 is in use in the horizontal direction, theupper shell 13 is normally disposed on the upper side. However, forconvenience sake of explanation, the upper side and the lower side arereversed in FIG. 1, and hence the upper shell 13 is placed in the lowerside.

[0067] The upper shell 13 is a thin disk-like member of substantially asquare-shape the front side of which is shaped as a circular arc asshown in FIGS. 1 and 4. At the central portion of the lower surface(surface in FIG. 1) of this upper shell 13, there is provided a circularupper concave portion 19 a into which substantially an upper half of themiddle shell 14 in the thickness direction can be fitted rotatably. Whenthe upper concave portion 19 a is provided on the central portion of thelower surface, a front edge portion 13 a, left and right side edgeportions 13 b, 13 c and a rear edge portion 13 d are formed on the outerperipheral edge of the upper shell 13. At substantially the centralportions of the front edge portion 13 a and the rear edge portion 13 dof the upper shell 13, there are provided positioning concave portions21 a and 21 b which are used to properly position the upper shellrelative to the lower shell 15.

[0068] On the outer peripheral edge of the upper concave portion 19 a ofthe upper shell 13, there are provided three circular-arc-like camgrooves 22, each having a predetermined length, which are continuedalong the circumferential direction. Then, there are provided the threecam grooves 22, whereby three lift up portions 23 (shown hatched in FIG.4), each having a predetermined length, between the adjacent cam grooves22 and 22. A cam portion 46 provided in the middle shell 14 is slidablyfitted into the three cam grooves 22.

[0069] The lower shell 15 is overlapped to the lower surface of theupper shell 13. As shown in FIGS. 1 and 6, the lower shell 15 has anoutward appearance shape which is substantially similar to that of theupper shell 13 and is formed of a substantially square thin disk-likemember whose front side is shaped as a circular arc. On the centralportion of the flat surface (surface hidden as the back in FIG. 1) ofthis lower shell 15, there is provided a circular lower concave portion19 b into which a substantially lower half portion of the thicknessdirection of the middle shell 14 is fitted rotatably. When this lowerconcave portion 19 b is provided on the central portion of the flatsurface of the lower shell, a front edge portion 15 a, left and rightside edge portion 15 b, 15 c and a rear edge portion 15 d are providedon the outer peripheral edge of the lower shell 15. On substantially acentral portion between the front edge portion 15 a and the rear edgeportion 15 d of the lower shell 15, there are provided positioningconvex portions 24 a and 24 b which are used to properly position thelower shell relative to the upper shell 13.

[0070] The convex portions 24 a, 24 b of the lower shell 15 arerespectively engaged with the concave portions 21 a, 21 b of the uppershell 13, whereby the upper and lower shells 13, 15 are properlypositioned and overlapped together in a predetermined state. The middleshell 14 is stored within a circular space formed of the upper and lowerconcave portions 19 a, 19 b formed within the upper and lower shells 13,15 so as to become freely rotatable. An opening portion 25 extended inthe front and back direction is bored at the central portion of thelower shell 15. This opening portion 25 is used to allow a turntable ofa disk rotary drive mechanism and an optical head of an optical pickupdevice to face to the optical disk 11 and is set to be wide enough sothat they can be inserted into and ejected from the opening portion.

[0071] Specifically, the opening portion 25 of the lower shell 15includes a table opening portion 25 a set at the central portion intoand from which the turntable is inserted and ejected and a head openingportion 25 b extended in the front and back direction of the tableopening portion 25 a. The shape of this opening portion 25 is consideredsuch that each of two optical heads can be simultaneously inserted intoand ejected from both sides of the table opening portion 25 a in thehead opening portion 25 b respectively. On the inner surfaces of bothends of the front and back direction of the head opening portion 25 b,there are respectively provided cover portions 26 a, 26 b which are usedto close the spacing between them and shutter members 18 a, 18 b whichwill be described later on. Further, within the lower concave portion 19b, there are provided a pair of operation convex portions 27 a, 27 bwhich become symmetrical with respect to the table opening portion 25 a.

[0072] The middle shell 14 is stored within the upper and lower concaveportions 19 a, 19 b formed by the upper shell 13 and the lower shell 15having the above arrangements, and the middle shell 14 and the uppershell 13 constitute a disk compartment 16 formed of a circular spacingportion. Within this disk compartment 16, there is stored the opticaldisk 11 with a predetermined spacing in the outside of the radiusdirection and in the thickness direction. This optical disk 11 is formedof a thin disk-like recording member having a center hole 11 a bored atthe central portion.

[0073] To one surface of the central portion of this optical disk 11,there is fixed a center hub 28 so as to cover the center hole 11 a by afixing means such as an adhesive agent. This center hub 28 is formed ofa magnetic material such as an iron plate attracted by a magnet. Aturntable of a disk rotary drive apparatus incorporated within a diskrecording and reproducing apparatus is fitted through the center hole 11a to the center hub 28. The center hub 28 is attracted by magnet forceof a magnet provided on the turntable. Consequently, the optical disk 11is chucked to the turntable and integrated in the rotation direction,whereby the optical disk is rotated at a predetermined velocity (e.g.,at a constant linear velocity) by driving a spindle motor to which theturntable is attached.

[0074] On one surface of this optical disk 11, there are provided aninformation recording area 29 a on which information can be recorded andwhich is opposed by an optical head of an optical pickup deviceincorporated within the disk recording and reproducing apparatus and anon-recording area 29 b on which information cannot be recorded. Thenon-recording area 29 b is comprised of an inner non-recording area 29 bhaving a predetermined width provided on the outside of the center hub23 which is in the inside of the optical disk 11 and an outernon-recording area 29 b having a predetermined width provided on theouter peripheral edge of the optical disk 11. An information recordingarea 29 a is provided between the inner and outer non-recording areas 29b and 29 b. As a material of a substrate of this optical disk 11,synthetic resins such as polycarbonate (PC) and polyolefin should besuitably used. It is needless to say that other synthetic resins can beused and that materials are not limited to the synthetic resins and thatvarious materials such as a glass material and an aluminum alloy whichcan be used as an information recording medium may be used.

[0075] An opening window 30 is bored at substantially central portionsof one side edge portions 13 b, 15 b of the upper and lower shells 13,15 so as to expose a part of the outer peripheral surface of the middleshell 14. This opening window 30 is comprised of an upper recess portion30 a provided on the joint portion of the upper shell 13 and a lowerrecess portion 30 b provided on the joint portion of the lower shell 15.Further, on one side edge portions 13 b, 15 b of the upper and lowershells 13, 15, there is provided a guide groove 31 which is extendedalong the joint surface in the front and back direction. This guidegroove 31 is provided in order to prevent a mis-insertion from beingcarried out when the disk cartridge 10 is loaded onto the disk recordingand reproducing apparatus. The opening window 30 is communicated withthe guide groove 31.

[0076] On the front corner portions of one side edge portions 13 b, 15 bof the upper and lower shells 13, 15, there is provided a lock storingportion 33 in which a lock member 32 can be stored rotatably. This lockstoring portion 33 is communicated with the concave portions 19 a, 19 band is communicated with the guide groove 31 through an opening hole 34bored through one side edge portions 13 b, 15 b. Further, on the lockstoring portion 33 of the upper shell 13, there is provided a supportshaft 35 which rotatably supports the lock member 32 in such a mannerthat it may be protruded from the lower shell 15 side.

[0077] This lock member 32 is formed of a lever-like member which isrotatably fitted into a supporting shaft 35 in such a manner that it canbe swung in the plane direction as shown in FIGS. 1 and 13. A stopperportion 36 having a plurality of teeth is provided at the lock member 32at its one end and an input portion 37 is provided at the other end inthe longitudinal direction. Further, the lock member 32 has a springpiece 38 integrally formed therewith and which is protruded in the samedirection so as to oppose to the stopper portion 36.

[0078] The lock member 32 having the above arrangement is fitted intothe supporting shaft 35 under the condition that the stopper portion 36is faced toward the concave portions 19 a, 19 b side. The spring piece38 is brought in contact with the inner surfaces of the front edgeportions 13 a, 15 a. Under spring force of this spring member 38, thestopper portion 36 is spring-biased toward the concave portions 19 a, 19b side. Concurrently therewith, the input portion 37 is extended throughthe opening hole 34 from the inside and is protruded into the guidegroove 31.

[0079] The middle shell 14 which is rotatably fitted into the upper andlower concave portions 19 a, 19 b of the upper shell 13 and the lowershell 15 has the arrangement shown in FIGS. 1 and 5 and the like. Thismiddle shell 14 includes a flat surface portion 40 formed of a disk-likethin plate material and a ring portion 41 continuously formed at theouter peripheral edge of the flat surface portion 40. The flat surfaceportion 40 of the middle shell 14 is comprised of a pair of semicirclepieces 40 a, 40 a formed as substantially semicircular shapes. Anopening portion 42 is formed by forming a spacing between chord sides ofthe two semicircle pieces 40 a, 40 a. This opening portion 42 has ashape and a size equal to those of the opening portion 25 of the lowershell 15.

[0080] Specifically, similarly to the opening portion 25, the openingportion 42 includes a table opening portion 42 a set at the centralportion of the flat surface portion 40 and into and from which theturntable is inserted and ejected and head opening portions 42 b, 42 bset at both sides of the diametrical direction of the table openingportion 42 a and to each of which an optical head is opposedrespectively. On the inner peripheral edge of the flat surface portion40 which surrounds the table opening portion 42 a, there is provided asupporting edge portion 40 b which supports the inner non-recording area29 b of the optical disk 11 from the lower direction in a free state.

[0081] On the outer peripheral surface of the ring portion 41 of themiddle shell 14, there is provided a gear portion 43 having a largenumber of gear teeth over a predetermined range of the peripheraldirection. As shown in FIG. 13, when the cartridge housing 12 isassembled, under the condition that the opening portion 42 of the middleshell 14 is made coincident with the opening portion 25 of the lowershell 15, this gear portion 43 is set at the position opposed to theopening window 30. The range of this gear portion 43 is set to be anangular extent slightly larger than the rotation angle of the middleshell 14. Specifically, as shown in FIGS. 15 to 19, when the pair ofshutter members 18 a, 18 b are completely closed such that the openingportion 42 is inclined by a maximum inclination angle relative to theopening portion 25, one end of the circumferential direction of the gearportion 43 is exposed to the opening window 30. Then, when the pair ofshutter members 18 a, 18 b are completely opened such that the middleshell 14 is rotated by a predetermined angle to cause the openingportion 42 to be laid on the opening portion 25, the other end of thecircumferential direction of the gear portion 43 is exposed to theopening window 30.

[0082] On the outside of one end of the gear portion 43 of this middleshell 14, there is provided a stopper portion 44 for limiting therotation movement amount of the middle shell 14 in such a manner that itmay be protruded toward the outside of the radius direction. Since thegear portion 43 and the stopper portion 44 are projected from the outerperipheral surface of the ring portion 41 to the outside as describedabove, relief grooves 45 a, 45 b are respectively provided on the uppershell 13 and the lower shell 15 at their corresponding portions so as toavoid them from contacting with the stopper portion 44 and the like suchthat they can be allowed to pass. Further, on one end face of the ringportion 41, there are provided three circular-arc-like cam portions 46(portions shown by a large number of points in FIG. 5), each having apredetermined length, continued in the circumferential direction. Thesecam portions 46 are respectively engaged with the three cam grooves ofthe upper shell 13 while the middle shell 14 is assembled on the uppershell 13. When this middle shell 14 is rotated at a predetermined angle,the respective cam portions 46 are overlaid on the three lift upportions 23, respectively.

[0083] On the other end face of the ring portion 41 of the middle shell14, there are provided two circular-arc-like protruded rail portions 47which are protruded in the opposite side of the cam portions 46. Theseprotruded rail portions 47, 47 are used to limit the pair of shuttermembers 18 a, 18 b from being moved in the outside of the radiusdirection. To avoid the contact with these protruded rail portions 47,47, cover portions 26 a, 26 a of the upper shell 13 have relief grooves48 extended in the circumferential direction, respectively as shown inFIG. 6. Further, on the flat surface portion 40 of the middle shell 14,there are respectively provided a pair of supporting apertures 49, 49which are used to support the pair of shutter members 18 a, 18 b suchthat the pair of shutter members become freely rotatable in the planedirection. The pair of supporting apertures 49, 49 are set on edgeportions of the head opening portions 42 b, 42 b with respect to thetable opening portion 42 a in a point-symmetrical fashion.

[0084] A shutter mechanism 18 that is attached to the middle shell 14through the pair of supporting apertures 49, 49 is comprised of the pairof shutter members 18 a, 18 b which are the same in shape and size. Thepair of shutter members 18 a, 18 b have the shape and structure shown inFIGS. 7 and 8. Specifically, the pair of shutter members 18 a, 18 b areeach formed of substantially a semicircular thin plate material. Atsubstantially a central portion of a chord side of each of the shuttermembers 18 a, 18 b, there are provided stepped portions 50 having apredetermined length in the direction perpendicular to the cord line.This stepped portion 50 forms at its both sides a convex-side jointportion 50 a and a concave-side joint portion 50 b.

[0085] On the respective joint portions 50 a, 50 b of the shuttermembers 18 a, 18 b, there are respectively provided overhang portions51, 51 which are overhung in the direction perpendicular to thedirection in which the chords are extended. Thus, in the pair of shuttermembers 18 a, 18 b, the end face of the convex-side joint portion 50 aand the end face of the concave-side joint portion 50 b are respectivelyopposed to each other, whereby the overhang portion 51 a of theconvex-side joint portion 50 a are overlapped on the overhang portion 51b of the concave-side joint portion 50 b. Shaft portions 52 which areprojected toward the overhang portions 51 side are respectively attachedto shaft attachment portions 50 c which are end portions of theconvex-side joint portion 50 a side of the chord sides of the shuttermembers 18 a, 18 b.

[0086] The shaft portions 52 are fitted into the supporting apertures 49of the flat surface portion 40, whereby the respective shutter members18 a, 18 b are rotatably attached to the middle shell 14. In this case,the pair of shutter members 18 a, 18 b are attached to the middle shellin such a manner that their chord sides are opposed to each other. As aresult, as shown in FIG. 7, when the pair of shutter members 18 a, 18 bare rotated so as to become distant from each other toward outside,respectively, the respective shutter members 18 a, 18 b are mounted onthe semicircular pieces 40 a such that they are hidden by thesemicircular pieces. On the other hand, when the pair of shutter members18 a, 18 b are inwardly rotated such that their joint portions 50 a, 50b are brought in contact with each other, a substantially circular coverportion is formed at the central portion of the opening portion 42 bythe pair of shutter members 18 a, 18 b as shown in FIG. 8.

[0087] Further, on the concave-side joint portions 50 b of the shuttermembers 18 a, 18 b, there are respectively provided open and closegrooves 53 which are used to open and close the shutter members 18 a, 18b. The open and close grooves 53 are extended in the radial directionfrom the shaft portions 52 of the shutter members 18 a, 18 b in whichthe open and close grooves are provided. The operation convex portions27 a, 27 b of the lower shell 15 are slidably engaged with the open andclose grooves 53. Further, at the end portions of the outsides of therespective open and close grooves 53, there are provided resilientpieces 54 formed by cutting their periphery and concave portions 53 awhich are used to relieve the operation convex portions 27 a, 27 b. Onthe circular-arc-like sides of the shutter members 18 a, 18 b, there areprovided close pieces 55 which are used to close openings left after theshaft portions 52 had been moved while the shutter is being closed.

[0088] The upper shell 13, the middle shell 14, the lower shell 15 andthe shutter members 18 a, 18 b having the above arrangements may be madeof synthetic resins such as ABS resin (acrylonitrile-butadiene-styreneresin) and HIPS (high impact polystyrene). However, it is needless tosay that they may be made of other synthetic resins and metal materialssuch as an aluminum alloy and a stainless steel.

[0089] The above middle shell 14, the operation convex portions 27 a, 27b, a rack rod 70 and the like constitute a shutter opening and closingmechanism. Then, the supporting apertures 49 and the shaft portions 52constitute a rotary coupling portion, and the operation convex portions27 a, 27 b and the open and close grooves 53 constitute a movementcoupling portion. Although not shown, the cartridge housing 12, forexample, of the disk cartridge 10 has at its rear corner portion awrite-protect mechanism for preventing information recorded on arecording medium such as an optical disk from being erased by mistake.Such write-protect mechanism can be comprised of an operation windowbored on the back of the cartridge housing 12, a write-protect pieceattached so as to open and close this operation window and the like.

[0090] The disk cartridge 10 having the above arrangement can beassembled with ease as follows, for example. An assembly work of thisdisk cartridge 10 is executed in the state in which the upper shell 13is disposed in the lower direction. First, the optical disk 11 isinstalled within the upper-side concave portion 19 a of the upper shell13. At that very moment, the optical disk 11 is inserted into theupper-side concave portion 19 a while its surface with the center hub 28is being faced to the lower directions. Next, the opening side of themiddle shell 14 is fitted into the upper-side concave portion 19 a so asto cover the optical disk 11. whereby the optical disk 11 is rotatablystored within the disk compartment 16 comprised of the middle shell 14and the upper shell 13. At that very moment, the direction in which theopening portion 42 of the middle shell 14 is extended is made coincidentwith the front and back direction of the upper shell 13 and one end ofthe gear portion 43 is faced to the opening window 30.

[0091] Next, the shutter mechanism 18 is assembled on the middle shell14. In this assembly work, while the chord sides of the pair of shuttermembers 18 a, 18 b are being opposed to each other, the shaft portions52 are respectively fitted into the supporting apertures 49 of the flatsurface portion 40 in this state. Then, the respective shutter members18 a, 18 b are separated from each other and are thereby overlapped onthe semicircular pieces 40 a of the middle shell 14. Concurrentlytherewith or before or after the above assembly work, the lock member 32is attached to the supporting shaft 35 of the lock storage portion 33.In that case, the spring piece 38 of the lock member 32 is brought incontact with the inner surface of the front edge portion 13 a of theupper shell 13, and the input portion 37 is projected from the openinghole 34 into the guide groove 31 under spring force of this spring piece38.

[0092] Next, the lower shell 15 is laid over the middle shell 14including the shutter mechanism 18, and the lower shell 15 is overlappedto the upper shell 13. At that time, the positioning convex portions 24a, 24 b of the lower shell 15 are fitted into the positioning concaveportions 21 a, 21 b of the upper shell 13, whereby the lower shell 15 isautomatically and properly positioned relative to the upper shell 13. Inthat case, when the pair of shutter members 18 a, 18 b are disposed atthe above positions, the pair of operation convex portions 27 a, 27 bprovided within the lower-side concave portion 19 b of the lower shell15 can be respectively opposed to the pair of open and close grooves 53.Therefore, only by overlapping the lower shell 15 on the upper shell 13without considering the positions of the pair of open and close grooves53, the pair of operation convex portions 27 a, 27 b can be engaged withthe pair of open and close grooves 53.

[0093] Thereafter, the lower shell 15 is overlapped to and fixed to theupper shell 13 by using a plurality of fixing screws. Thus, the assemblywork of the disk cartridge 10 is completed. In this case, without usinga fixing means comprised of independent members such as fixing screws,the joint surfaces of the upper shell 13 and the lower shell 15 candirectly be joined by using a suitable means such as an adhesive agent.As described above, according to the disk cartridge 10 of thisembodiment, the number of assemblies can be decreased and the assemblywork can be carried out extremely easily.

[0094] In this case, the joint portions 50 a, 50 b of the pair ofshutter members 18 a, 18 b have the overhang portions 51 a, 51 b, eachhaving about half the thickness and these overhang portions 51 a, 51 bare inserted beneath the other joint portions 50 a, 50 b, respectively.Therefore, since the overall arrangements of the joint portions 50 a, 50b are properly overlapped with each other, a labyrinth effect can beachieved so that the disk cartridge can be prevented from being smudgedby dusts and the like over the whole length of the joint portions 50 a,50 b. In addition, when the joint portions 50 a, 50 b are pressedinwardly, external force applied to the joint portions 50 a, 50 b isreceived by the overhang portions 51 a, 51 b located at the inside.Consequently, the engagement state between the joint portions 50 a and50 b can be strengthened more by the overhang portions 51 a, 51 b,whereby the shutter members can be prevented from being deformed and thedisk cartridge can be prevented more reliably from being smudged bydusts and the like.

[0095]FIG. 2 shows the state presented before the disk cartridge 10having the above arrangement is loaded on the disk recording andreproducing apparatus. Specifically, the pair of shutter members 18 a,18 b of the shutter mechanism 18 completely close the opening portion 25of the lower shell 15 and the opening portion 42 of the middle shell 14due to its own tare and frictional force generated between the lowershell 15 and the middle shell 14. Further, the three cam portions 46 ofthe middle shell 14 are projected from the three cam grooves 22 of theupper shell 13 and are thereby laid over the lift up portions 23. As aconsequence, the pair of shutter members 18 a, 18 b are sandwichedbetween both sides by the upper shell 13 and the middle shell 14.

[0096] Further, as shown in FIG. 13 and the like, the stopper portion 36is engaged with the gear portion 43 of the middle shell 14 under springforce of the spring piece 38 of the lock member 32. Consequently, thepair of shutter members 18 a, 18 b are doubly locked by a holdingmechanism based on cam elevation operations and a lock mechanism basedon the lock member 32. Accordingly, the state in which the openingportions 25, 42 are closed by the shutter mechanism 18 can be held withhigh reliability and the shutter mechanism 18 can reliably be preventedfrom being opened by mistake due to some cause such as vibrations.

[0097] When the disk cartridge 10 in this state is inserted into a diskrecording and reproducing apparatus 60 as shown in FIGS. 25 and 26, thelock member 32 is released from the locked state by a shutter openingand closing mechanism provided in this disk recording and reproducingapparatus 60. Thereafter, this shutter opening and closing mechanismopens the shutter mechanism 18 to open the opening portions 25, 42. Themanner in which this shutter mechanism 18 is opened and closed will bedescribed in detail later on.

[0098] Next, the disk recording and reproducing apparatus 60 will bedescribed. As shown in FIGS. 25 and 26, this disk recording andreproducing apparatus 60 comprises an outer case 61 formed of a hollowhousing, a recording and reproducing apparatus body 62 stored withinthis outer case 61 and the like. The outer case 61 includes a case body63 which is opened in the upper surface and the front, a case lid 64detachably attached to the upper portion so as to close the uppersurface of the case body 63, a front panel 65 detachably attached to thefront portion so as to close the fronts of the case body 63 and the caselid 64 and the like.

[0099] The case body 63 is provided with four leg assemblies 63 a whichare projected in the lower direction. The disk recording and reproducingapparatus 60 is supported by these leg assemblies 63 a and therebyattached to the proper position. The front panel 65 is formed of anoblong plate-like member, and an oblong cartridge slot 66 is formed onthe upper portion of the front panel. The cartridge slot 66 hasapproximately the same dimension as that of the front side of the diskcartridge 10. This cartridge slot 66 is constantly closed by an open andclose lid 67 disposed on the inside of the cartridge slot.

[0100] This open and close lid 67 is pressed by the front portion of thedisk cartridge 10 and the disk cartridge is inserted into the cartridgeslot at its predetermined position. As a result, the disk cartridge 10is automatically loaded into the disk recording and reproducingapparatus by a loading mechanism not shown. Then, the disk cartridge 10transported by the loading mechanism is properly located at apredetermined position and fixed thereto within the disk recording andreproducing apparatus 60. Concurrently therewith or before and after theabove operation, the shutter opening and closing mechanism provided inthe disk recording and reproducing apparatus 60 operates the shuttermechanism 18 to open the opening portions 25, 42.

[0101] Thereafter, a turntable 68 a of a disk rotary drive apparatus 68and an optical head 69 a of an optical pickup device 69 are entered intothe opening portions 25, 42 thus opened. Then, the turntable 68 a isengaged with the center aperture 11 a of the optical disk 11 and thecenter hub 28 is attracted and held by a magnet incorporated within theturntable 63 a. Concurrently therewith or before and after the aboveoperation, the optical head 69 a is approached to a predeterminedposition of the information recording area 29 a of the optical disk 11,whereby the disk recording and reproducing apparatus 60 becomes able torecord an information signal on the optical disk 11 and to reproduce arecorded information signal from the optical disk.

[0102] The recording and reproducing apparatus body 62 of the diskrecording and reproducing apparatus 60 comprises constituents shown inFIG. 24, for example. Specifically, the recording and reproducingapparatus body 62 includes three control apparatus of a systemcontroller S1, a memory controller S5 and a drive controller D1. Thesystem controller S1 and the memory controller S5 are directlyconnected, and a read-only memory apparatus (ROM) S2 and a read andwrite memory apparatus (RAM) S3 are connected to a connection linebetween the system controller and the memory controller. Further, amemory S4 and MPEG 2 (moving picture compression system applied toexisting television broadcasting capable of 3M to 40 Mbps, HDTV andbroadband ISDN) encoder S6 and decoder S7 are connected to the memorycontroller S5. Further, a control panel S8 and a remote controlreceiving section S9 are connected to the system controller S1.

[0103] An ECC D4 is connected to the drive controller D1, and a memoryapparatus (ROM) D2, a memory apparatus (RAM) D3, a servo circuit D6 andan address decoder D7 are connected to a connection line between thedrive controller and the ECC. Further, the drive controller D1 isconnected with a recording error judgment circuit D8 for judging whetheror not an error occurred upon recording. This drive controller D1 isconnected through a command interface to the system controller S1. Thedrive controller is connected through the ECC D4 and a data interface tothe memory controller S5 and a modem circuit D5. Then, the modem circuitD5 is also connected to the optical head 69 a of the optical pickupdevice 69.

[0104] The servo circuit D6 is connected to a spindle motor 68 which isserving as a disk rotary drive apparatus, the optical pickup device 69and the recording error judgment circuit D8. Further, the optical pickupdevice 69 is connected to an address decoder D7, and this addressdecoder D7 is also connected to the recording error judgment circuit D8.

[0105] When the disk cartridge 10 is inserted into the disk recordingand reproducing apparatus 60 having the above arrangement from thecartridge slot 66, as shown in FlG. 13, a rack rod 70 which shows apractical example of the shutter opening and closing mechanismincorporated within the disk recording and reproducing apparatus 60 isentered into the guide groove 31 formed on one side portion of the diskcartridge 10, whereby the input portion 37 of the lock member 32projected into the guide groove 31 is pushed into the lock storageportion 33 by pressing force of the rack rod 70 against spring force ofthe spring piece 38. Further, when the rack rod 70 is advancedrelatively, the tip end of the gear portion 70 a is meshed with the gearportion 43 of the middle shell 14.

[0106] This gear portion 43 is meshed with the gear portion 70 a of therack rod 70, whereby the middle shell 14 is rotated in response to themoved amount of the rack rod 70 as shown in FIGS. 13 to 19. FIGS. 13 and14 show the state presented before the gear portion 70 a of the rack rod70 is meshed with the gear portion 43 of the middle shell 14. In thisstate, the convex-side joint portion 50 a and the concave-side jointportion 50 b of the pair of shutter members 18 a, 18 b are urged againstwith each other and are thereby closely contacted with each other. Atthat very time, since the opening portion 42 of the middle shell 14 islocated at the inclined position relative to the opening portion 25 ofthe lower shell 15, although only the central portion in which the twoopening portions 25, 42 are overlapped with each other is opened, thatopening portion is closed by the pair of shutter members 18 a, 18 b.Accordingly, the disk compartment 16 can be prevented from being smudgedby dusts and the like from the overlapping portion of the openingportions 25, 42.

[0107] The shaft attachment portions 50 c of the pair of shutter members18 a 18 b are interposed at the portions in which the opening portions25 and 42 are close to each other with an acute angle, and the shaftattachment portion 50 c is located at the inside of one cover portion 26b, thereby removing the space. The closing piece 55 is interposed at theinside of the other cover member 26 a, and this closing piece 55 islocated at the inside of the other cover member 26 a, thereby removingthe space. Further, the open and close grooves 53 provided on the pairof shutter members 18 a, 18 b are respectively closed by the lower shell15. Therefore, since all spaces from the opening portion 25 of the lowershell 15 to the opening portion 42 of the middle shell 14 are completelyclosed by the pair of shutter members 18 a, 18 b, the disk compartment16 can be prevented from being smudged by dusts and the like through theopening portions 25, 42.

[0108] In this state, when the rack rod 70 is being entered into theguide groove 31 as the disk cartridge 10 is being inserted into the diskrecording and reproducing apparatus and the gear portion 70 a and thegear portion 43 of the middle shell 14 commence to be meshed with eachother, the middle shell 14 is rotated in the counter-clockwise directionin FIG. 13. In this case, in the initial state in which the middle shell14 commences to rotate, as shown in FIGS. 20C and 21A, the cam portion46 is laid over the lift up portion 23 and sandwiches the pair ofshutter members 18 a, 18 b between it and the upper shell 13 so thatrelatively large force is required to rotate the middle shell 14. Whenthe middle shell 14 is rotated against large frictional force generatedfrom the cam portion 46 so that the cam portion 46 passes the lift upportion 23 and enters the cam groove 22 as shown in FIGS. 20B and 21B,frictional force of the cam portion 46 is lost. Consequently, the middleshell 14 will be able to rotate extremely lightly and smoothly.

[0109] At that time, while the respective shaft portions 52 of the pairof shutter members 18 a, 18 b are similarly rotated as the middle shell14 is rotated, the operation convex portions 27 a, 27 b of the lowershell 15 are slidably engaged with the open and close grooves 54provided on the other end side. The pair of operation convex portions 27a, 27 b are provided on the lower shell 15 and the operation convexportions 27 a, 27 b are never moved. On the other hand, the open andclose grooves 53 are extended in the direction S connecting the shaftportion 52 and the operation convex portion 27 b (or 27 a) in such amanner that they can be relatively moved within the operation convexportions 27 a, 27 b as the shutter members 18 a, 18 b are rotated.

[0110] As a result, the operation convex portion 27 b (or 27 a) is movedwithin the open and close groove 53 toward the shaft portion 52 side inresponse to the rotation amounts of the shutter members 18 a, 18 b.Thus, in each of the shutter members 18 a, 18 b, the shaft portion 52 ismoved toward the corresponding operation convex portion 27 b (27 a)side. Consequently, the respective shutter members 18 a, 18 b are movedon the corresponding semicircular pieces 40 a from the state shown inFIG. 15 through the states shown in FIGS. 16, 17 and 18 as shown in FIG.19. Thus, the respective shatter members 18 a, 18 b are overlapped onthe semicircular pieces 40 a so that the upper and lower openingportions 25, 42 are opened completely as shown in FIG. 9 and the like.Therefore, a part of the optical disk 11 stored within the diskcompartment 16 is exposed through the opening portions 25, 42.

[0111] As a consequence, as shown in FIG. 12, the turntable 68 a and theoptical head 69 a can be inserted into the opening portions 25, 42.Accordingly, the turntable 68 a or the like is moved toward the diskcartridge 10 side or the disk cartridge 10 is moved toward the turntable68 a side, whereby the turntable 68 a is entered into the table openingportion 25 a provided at the central portion and the optical head 69 ais entered into the head opening portion 25 b provided at both sides. Asa result, the optical disk 11 is loaded on and chucked to the turntable65 a and the optical head 69 a is opposed to the information recordingarea 29 a of the optical disk 11 with a predetermined space with theresult that the disk recording and reproducing apparatus 60 becomes ableto reproduce or record an information signal from or on the informationrecording area 29 a of the optical disk 11.

[0112] Accordingly, the recording and reproducing apparatus body 62 isoperated, the optical disk 11 is rotated by driving the spindle motor 68through the turntable 68 a, laser light is emitted from the optical head69 a by driving the optical pickup device 69 and the information signalrecorded before can be read out from the information recording area 29 aor a new information signal can be recorded on the information recordingarea 29 a. Thus, the recording and reproducing apparatus body 62 canreproduce or record the information signal.

[0113] After the information signal had been reproduced or recorded asdescribed above, when a user operates a cartridge eject button (notshown) provided on the disk recording and reproducing apparatus 60, forexample, the disk cartridge 10 is ejected from the disk recording andreproducing apparatus 60 through the operation of the loading mechanism.Specifically, when the disk cartridge 10 is moved toward the cartridgeslot 66 side by the eject operation of the loading mechanism, the rackrod 70 is retreated relatively.

[0114] When the rack rod 70 is retreated, the middle shell 14 and thepair of shutter members 18 a, 18 b are operated in the manner oppositeto the above manner in which the optical disk is inserted into therecording and reproducing apparatus. Specifically, in the state in whichthe pair of shutter members 18 a, 18 b are completely opened as shown inFIG. 19, the middle shell 14 and the pair of shutter members 18 a, 18 bare rotated in the clockwise direction and the middle shell and the pairof shutter members are changed to the state shown in FIG. 15 through thestates shown in FIGS. 18, 17 and 16. In the states shown in FIGS. 19 to15, the cam portion 46 of the middle shell 14 exists within the camgroove 22 so that the middle shell 14 can be rotated by small force F.

[0115] Next, when the middle shell 14 is changed from the state shown inFIG. 15 to the state shown in FIG. 13, since the cam portion 46 isbrought in contact with the lift up portion 23 and then laid over thelift up portion 23 so that the above frictional force is applied to therotation of the middle shell 14. Then, immediately before the closedstate shown in FIG. 13, the operation convex portion 27 b (or 27 a)moves the open and close groove 53 to the outermost portion so that theopen and close groove comes in contact with and presses the resilientpiece 54. As a result, spring force X is generated in the resilientpiece 54 by pressing force of the operation convex portion 27 b (or 27a). Under spring force X of this resilient piece 54, urging contactforce Y which is acting on the other shutter member 18 a (or 18 b) isgenerated in the central stepped portion 50.

[0116] Since this urging contact force Y is generated in both of thepair of shutter members 18 a, 18 b, the airtightness of the pair ofshutter members 18 a, 18 b can be improved more by their urging contactforce Y. Accordingly, the disk compartment 16 can be more effectivelyprevented from being smudged by dusts and the like by improving thedustproof property at the joint portion of the pair of shutter members18 b, 18 b.

[0117] Thereafter, after the gear portion 70 a of the rack rod 70 hadbeen disengaged from the gear portion 43, the rack rod 70 is passedthrough the opening hole 34, whereby the input portion 37 of the lockmember 32 is projected from the opening hole 34 into the guide groove31. Concurrently therewith, the stopper portion 36 is moved to theinside and is thereby meshed with the gear portion 43. As a result, themiddle shell 14 is locked by the lock member 32 and its rotation isthereby stopped. Then, as shown in FIGS. 10 and 11, the whole of theopening portions 25, 42 is completely closed by the pair of shuttermembers 18 a, 18 b.

[0118]FIGS. 22 and 23 show a disk cartridge according to a secondembodiment of the present invention. A disk cartridge 80 shown in thisembodiment is of one-head type disk cartridge for use in a diskrecording and reproducing apparatus using one head. As will be clearfrom FIG. 22, this disk cartridge 80 differs from the disk cartridge 10shown in FIG. 1 and the like only in a lower shell 85. Therefore,elements and parts identical to those of FIG. 1 are marked with theidentical reference numerals and need not be described. Only an openingportion 86 of the lower shell 85 having different arrangement will bedescribed.

[0119] The opening portion 86 of the lower shell 85 has the same shapeand arrangement as those of the opening portion 25 of the above lowershell 15 from which only one head opening 25 b is removed. Other shapesand arrangements are the same. The one head disk cartridge 80 can easilybe manufactured by using the one head lower shell 85 instead of the2-head lower shell 15, and hence the present invention can easily copewith a one-head type disk recording and reproducing apparatus and atwo-head type disk recording and reproducing apparatus. In addition,according to this embodiment, the manufacturing and assembling lines canbe made common and the present invention can properly cope with users'needs.

[0120] While the present invention has been described so far, thepresent invention is not limited to the above embodiments. For example,while the optical disk has been used as the information recording mediumas described above, the present invention is not limited thereto and canbe applied to magnetic disks such as a magnetooptical disk and a floppydisk and other various kinds of disk-like recording mediums. Further,while the present invention has been applied to the disk recording andreproducing apparatus for both of recording and reproduction as theinformation recording and reproducing apparatus as described above, thepresent invention is not limited thereto and can, of course, be appliedto a disk recording apparatus or a disk reproducing apparatus which iscapable of either recording or reproducing a disk.

[0121] While the opening portions 42, 25 are provided on the middleshell 14 and the lower shell 15 of the cartridge housing 12 as describedabove, the present invention is not limited thereto and the openingportion may be provided on the upper shell 13, for example, so that thedisk can be accessed simultaneously from upper and lower directions ofthe cartridge housing 12. Further, the disk compartment may be comprisedof the middle shell and the lower shell, the disk-like recording mediummay be stored within the disk compartment and the opening portion may beprovided on the upper shell. As described above, the present inventionmay be variously modified without departing from the gist thereof.

[0122] As set forth above, according to the disk cartridge as claimed inclaim 1 of the present invention, in the disk cartridge comprising thecartridge housing having the disk compartment, the disk-like recordingmedium and the pair of shutter members, since the disk cartridgeincludes the shutter opening and closing mechanism for moving the pairof shutter members based on the rotation of the middle shell to therebyopen and close the opening portion, the middle shell is rotated and thepair of shutter members are rotated by the operation of the shutteropening and closing mechanism so that the opening portion from which apart of the disk-like medium is exposed is smoothly and reliably beopened and closed. Therefore, the disk compartment can be prevented frombeing smudged by very small dusts and the like by reducing the spacebetween the pair of shutter members and the cartridge housing, and thereis provided the cartridge housing with excellent dustproof property.Moreover, in the disk cartridge thus provided, the number of parts arereduced, the structure is simple, the productivity is superior, thethickness is thin, the size is compact, and the dustproof property isexcellent since the disk cartridge is constituted of three shells of theupper, lower, and middle, the pair of shutter members and the lockmember.

[0123] According to the disk cartridge as claimed in claim 2 of thepresent invention, since the pair of shutter members are comprised of acombination of two substantially semicircular same plate materials andthe pair of shutter members are disposed symmetrically across theopening portion on the same plane, the opening portion of the wide rangecan be opened and closed while the areas of the shutter members arebeing reduced. Thus, while an efficiency with which the opening portionis opened and closed is being increased, the whole of the disk cartridgecan be made compact and thin.

[0124] According to the disk cartridge as claimed in claim 3 of thepresent invention, since the shutter opening and closing mechanismincludes the rotary coupling portion and the movement coupling portionso that the pair of shutter members are opened and closed by therotation of the middle shell to thereby open and close the openingportion, the pair of shutter members are rotated based on the rotationof the middle shell so that the opening portion can smoothly andreliably be opened and closed.

[0125] According to the disk cartridge as claimed in claim 4 of thepresent invention, since the rotary coupling portion is comprised of acombination of a shaft portion and an engagement hole and the movementcoupling portion is comprised of a combination of a guide groove and anoperation convex portion, the pair of shutter members can be operatedwith high reliability and the opening portion can smoothly and reliablybe opened and closed.

[0126] According to the disk cartridge as claimed in claim 5 of thepresent invention, since the opening portion is shaped such that itextends in the diametrical direction through the central portions of themiddle shell and the like, two head portions can simultaneously be facedinto the opening portion, whereby two operations (e.g., writing andreading of information signal can be carried out, writing or reading oftwo places can be carried out simultaneously, etc.) can be carried outat the same time. So, the very convenient disk cartridge which canexecute plural functions at the same time is provided.

[0127] According to the disk cartridge as claimed in claim 6 of thepresent invention, since the disk cartridge comprises the shutteropening and closing mechanism for opening and closing the openingportion by moving the pair of shutter members based on the rotation ofthe middle shell and the elevation mechanism for moving the middle shellin the direction perpendicular to the rotation direction based on therotation of the middle shell, the pair of shutter members can smoothlyand reliably be rotated by rotating the middle shell and the middleshell can be ascended and descended and pressed against the upper shellor the lower shell when the middle shell is rotated. Therefore, thespace can be removed or reduced by closely contacting the middle shellwith the upper shell or the lower shell so that the disk compartment canbe prevented from being smudged by very small dusts and the like,thereby improving the dustproof property of the cartridge housing.Moreover, the thickness of the cartridge housing can be decreased andthe space factor can be improved and the whole of the disk cartridge canbe made compact and thin as well as the dust-proof property isexcellent.

[0128] According to the disk cartridge as claimed in claim 7 of thepresent invention, since the pair of guide grooves are provided on oneof the pair of shutter members and the cartridge housing and the pair ofoperation convex portions are provided on the other of the pair of guidegrooves and the pair of operation convex portions and the guide groovesare moved along the operation convex portions based on the rotation ofthe middle shell, the pair of shutter members can smoothly and reliablybe moved, whereby the opening portion of the wide range can be openedand closed.

[0129] According to the disk cartridge as claimed in claim 8 of thepresent invention, since the pair of shutter members are comprised ofthe combination of two substantially semicircular same plate materials,the guide grooves are provided on one side portions of the respectiveshutter members, the pivots are provided on the other side portions andthe pivots are supported by the middle shell so as to become freelyrotatable, the opening portion of the wide range can be opened andclosed while the areas of the shutter members are being reduced. Thus,an efficiency with which the opening portion is opened and closed can beincreased, and the whole of the disk cartridge can be made compact andthin.

[0130] According to the disk cartridge as claimed in claim 9 of thepresent invention, since the cam grooves or the cam convex portions areprovided on the upper shell or the lower shell and the cam convexportions or the cam grooves are provided on the middle shell to therebyconstitute the elevation mechanism, the pair of shutter members can besandwiched by the upper shell or the lower shell and the middle shell asthe middle shell is rotated, the space can be removed by closelycontacting the middle shell with the upper shell or the lower shell sothat the disk compartment can be prevented from being smudged by verysmall dusts and the like. Thus, the dustproof property of the cartridgehousing can be improved.

[0131] According to the disk cartridge as claimed in claim 10 of thepresent invention, in the disk cartridge including the cartridge housinghaving the disk compartment, the disk-like recording medium and the pairof shutter members, since the gear portion formed around the outerperipheral surface of the middle shell is exposed from the openingwindow provided on the side surface of the upper shell and the lowershell, the middle shell can be rotated by the simple shutter opening andclosing mechanism such as the rack rod disposed on the outside, and thepair of shutter members can smoothly and reliably be rotated based onthe rotation of the middle shell. Therefore, the shutter opening andclosing mechanism can be constructed extremely easily. In addition, thedisk compartment can be prevented from being smudged by very small dustsand the like by miniaturizing the space between the pair of shuttermembers and the cartridge housing. Thus the dustproof effect of thecartridge housing can be improved and the disk cartridge can bedecreased in size and thickness and improved in space factor. There canbe achieved the effects that the whole of the disk cartridge can be madecompact and thin.

[0132] According to the disk cartridge as claimed in claim 11 of thepresent invention, since the disk cartridge has the arrangement in whichthe pair of shutter members are comprised of a combination of the sametwo substantially semicircular plate materials, the respective shuttermembers are symmetrically disposed across the opening portion, the guidegrooves are provided on one side portions of the chord sides of therespective shutter members and the shaft portions provided on the otherside portions are rotatably supported by the middle shell, the openingportion of the wide range can be opened and closed while the areas ofthe shutter members are being decreased. Thus, the opening and closingefficiency of the opening portion can be improved and the whole of thedisk cartridge can be made compact and thin.

[0133] According to the disk cartridge as claimed in claim 12 of thepresent invention, since the disk cartridge has the arrangement in whichthe pair of guide grooves are provided on one of the pair of shuttermembers and the cartridge housing and the pair of operation convexportions are provided on the other so that the guide grooves may be bemoved along the operation convex portions based on the rotation of themiddle shell, the pair of shutter members are opened and closed by therotation of the middle shell to thereby open and close the openingportion and the pair of shutter members can be rotated smoothly andreliably.

[0134] According to the disk cartridge as claimed in claim 13 of thepresent invention, since the disk cartridge has the arrangement in whichthe opening portion is extended through the central portion of thecartridge housing to the diametrical direction of the disk-likerecording medium the two head portions can be inserted into and ejectedfrom the opening portion simultaneously so that the two head portionsare faced into the opening portion simultaneously and two operations(e.g., writing and reading of an information signal, writing or readingof an information signal at two places at the same time, etc.) can becarried out simultaneously. There can be achieved the effect that theuseful disk cartridge can be provided.

[0135] Having described preferred embodiments of the present inventionwith reference to the accompanying drawings, it is to be understood thatthe present invention is not limited to the above-mentioned embodimentsand that various changes and modifications can be effected therein byone skilled in the art without departing from the spirit or scope of thepresent invention as defined in the appended claims.

What is claimed is:
 1. A disk cartridge comprising: a cartridge housing in which a disk compartment is formed between an upper shell and a middle shell or between said middle shell and a lower shell by overlapping said upper shell, said middle shell and said lower shell and in which said middle shell is rotatably supported by said upper shell and said lower shell; a disk-like recording medium stored within said disk compartment so as to become freely rotatable; a pair of shutter members attached to said middle shell in such a manner that they can be moved in the flat surface direction on the same plane; and a shutter opening and closing mechanism for opening and closing an opening portion by moving said pair of shutter members based on the rotation of said middle shell.
 2. A disk cartridge according to claim 1 , wherein said pair of shutter members are comprised of a combination of two substantially semicircular same plate materials and said shutter members are symmetrically disposed on one surface side of said middle shell across said opening portion.
 3. A disk cartridge according to claim 1 , wherein said shutter opening and closing mechanism includes rotary coupling portions respectively provided on one side portions of said pair of shutter members and which are coupled to said middle shell so as to become freely rotatable and movement coupling portions respectively provided on the other side portions of said respective shutter members and which are coupled to said lower shell or said upper shell so as to become movable relatively and said shutter opening and closing mechanism opens and closes said opening portion by rotating said pair of shutter members around said rotary coupling members based on the rotation of said middle shell to thereby relatively move said movement coupling portions.
 4. A disk cartridge according to claim 3 , wherein said rotary coupling portion is comprised of a combination of a shaft portion provided on one of said pair of shutter members and said middle shell and an engagement hole provided on the other of said pair of shutter members and said middle shell, said movement coupling portion is comprised of a combination of a guide groove provided on one of said pair of shutter members and said lower shell or said upper shell and an operation convex portion provided on the other of said pair of shutter members and said lower shell or said upper shell and said pair of shutter members are enabled to execute said open and close operation of said opening portion by moving said guide groove along said operation convex portion based on the rotation of said middle shell.
 5. A disk cartridge according to claim 1 , wherein said opening portion is extended in the linear direction through respective central portions of said middle shell and said lower shell or said middle shell and said upper shell.
 6. A disk cartridge according to claim 1 , wherein an elevation mechanism for moving said middle shell in the direction perpendicular to said rotation direction based on the rotation of said middle shell so that said middle shell is pressed against said lower shell or said upper shell.
 7. A disk cartridge according to claim 6 , wherein said shutter opening and closing mechanism includes a pair of guide grooves provided on one of said pair of shutter members and said cartridge housing and a pair of operation convex portions provided on the other of said pair of shutter members and said cartridge housing and which are slidably engaged with said guide grooves, and said pair of shutter members are enabled to open and close said opening portion by moving said guide grooves along said operation convex portions based on the rotation of said middle shell.
 8. A disk cartridge according to claim 6 , wherein said pair of shutter members are comprised of a combination of a pair of substantially semicircular same plate-like materials, said pair of shutter members are symmetrically disposed on one surface side of said middle shell across said opening portion, said guide grooves are provided on one side portions of chord sides of said respective shutter members and pivots provided on the other side portions of said chord sides are supported by said middle shell so as to become freely rotatable.
 9. A disk cartridge according to claim 6 , wherein said elevation mechanism is comprised of a plurality of circular-arc-like can grooves or cam convex portions provided in the circumferential direction of said upper shell or said lower shell at a predetermined interval and which are concaved or convexed in said direction in which said upper shell, said middle shell and said lower shell are overlapped and cam convex portions or cam grooves provided in the circumferential direction of said middle shell at a predetermined interval and which are slidably engaged with said cam grooves or said cam convex portions.
 10. A disk cartridge according to claim 1 , wherein a gear portion is provided on the outer peripheral surface of said middle shell over a predetermined range of the circumferential direction and an opening window from which a part of said gear portion is exposed is bored through the side surface of said upper shell and said lower shell.
 11. A disk cartridge according to claim 10 , wherein said pair of shutter members are comprised of a combination of a pair of substantially semicircular same plate materials, said pair of shutter members are symmetrically disposed on one surface of said middle shell across an opening portion, said guide groove is provided on one side portion of a chord side in each of said shutter members and a shaft portion provided on the other side portion of said chord side is rotatably supported by said middle shell.
 12. A disk cartridge according to claim 11 , wherein a pair of guide grooves are provided on one of said pair of shutter members and said cartridge housing, a pair of operation convex portions which are slidably engaged with said guide grooves are provided on the other of said pair of shutter members and said cartridge housing, said guide grooves are moved along said operation convex portions based on the rotation of said middle shell, whereby said pair of shutter members are enabled to open and close said opening portion.
 13. A disk cartridge according to claim 10 , wherein said opening portion is extended in the linear direction through central portions of said middle shell and said lower shell or said middle shell and said upper shell. 